Goofs

(at around 1h 30 mins) Jonas has three explosive spears when facing off to three megs whilst on a jet ski. After throwing one and missing, and then throwing a second one and killing one of the megs. He still has two spears for several cuts after.

(at around 1h 27 mins) When running from the creatures, Rigas is clearly very far ahead of DJ, but as the shot changes, DJ is suddenly in front of Rigas.

(at around 1h 10 mins) Just after DJ shows his big gun for the first time, it's confiscated by the mercenaries. Right at the end of the film (at around 1h 40 mins) he's seen using it against the amphibious dogs, even though we're not shown him retrieving the weapon, and there being several instances before this scene where he would have had ample opportunity to use it.

(at around 7 mins) Jonas is swooped up along with many gallons of seawater. He's then dumped on a tarmac along with all that water, but as he walks away from the plane, he leaves no wet footprints on the concrete.

(at around 13 mins) In the first movie Meiying is 8 years old. This movie is set 4 years after making her 12, however in this movie is clearly stated she is 14.

(at around 57 mins) You cannot just breathe all the air out of your skull and be able to free swim the 25,000 feet below sea level wearing no suit.

(at around 25 mins) The thermocline is shown as a near solid, thick layer deep in the water column. In reality it is just a layer where there is a sharp change in temperature with no other changes in physical properties. It can occur anywhere and at any depth.

The snapper lizards being portrayed as equally agile running on land as swimming 25,000 feet below sea level is plainly impossible.

(at around 1h 6 mins) Montes is seen grabbing onto a buoy to float back to the surface; ascending from 25,000 feet of depth that fast would certainly kill him, due to decompression, but he's then seen running around and fighting without any problem.

(at around 2 mins) The opening scene shows a meg devouring a dinosaur 65 million years ago. Megalodons never shared the Earth with dinosaurs, evolving between 28 and 23 million years ago, approximately 40 million years after dinosaurs went extinct.

(at around 1h 23 mins) Hillary is wearing high heels when leaving the helicopter. When the lizard creature drags her out of the helicopter, you'll notice the heel part of her sandal is missing, making it look like she had on flats.

(at around 1h 18 mins) The XU-018 number on one of the helicopter's fuselage indicates that it is registered in Cambodia. The film's end credits show Phuket, Thailand as being the filming location where its aircraft registration number is HS.

(at around 1h 23 mins) When being pursued by the creatures, Hillary jumps out of the helicopter and says "Shit", but her mouth can clearly be seen not moving as she speaks.

Sea creatures have been trapped below the thermocline for millions of years. Yet the aquatic snapper lizards can walk and breathe perfectly well on land.

Down below in the sea, the aquatic snappers swims away from the group when a bright light is shone upon them. Yet on land, they walk in broad daylight.

(at around 26 mins) Sal refers to the large megalodon, saying, "That's the apex predator". "Apex predator" refers to a species, not an individual.

(at around 20 mins) One character says they are launching in T minus 20. This is incorrect. The current time would be T minus 20, as the launch is 20 minute from now. Launching in T minus 20 would mean they launched 20 minutes ago.